Method and device for forming metal frames for reinforced concrete and metal frame formed therewith

Abstract: Method for forming metal frames for reinforced concrete, which entails the formation of a lattice comprisig stirrups (30) that have a closed or open profile, are arranged on appropriately spaced parallel planes, and are fixed to at least two thin longitudinal auxiliary rods (29) which are welded externally to the stirrups (30); and the rigid coupling of a series of longitudinal rods (61) to said lattice, said rods (61) being inserted inside said stirrups (30) and tied to at least some of them.

Description: The present invention relates to a method and to a device for forming metal frames for reinforced concrete, as well as to the metal frame obtained therewith. It is known that metal lattices or frames, formed by longitudinal rods mutually connected by appropriately spaced transverse stirrups, are commonly used in order to form the reinforcement of pillars and beams made of reinforced concrete. The stirrups usually form a closed path, for example a quadrilateral one, with overlapping ends; the longitudinal rods are inserted into the profile formed by said stirrups, for example at the corners of the profile. The most commonly used method for forming said metal frames entails the manual insertion of the stirrups on the longitudinal rods, which are grouped and supported by appropriate supports. After appropriately mutually spacing the stirrups and after manually marking their position, some of the longitudinal rods are tied to the upper portion of said stirrups. For example, in the case of the above mentioned stirrups with a quadrilateral profile, two longitudinal rods are tied at the corners of the upper horizontal side of the profile. The remaining longitudinal rods are then inserted on the lower portion of the stirrups and also tied to said stirrups. According to the requirements, additional longitudinal rods can of course be coupled to the metal frame thus formed, for example in intermediate positions on the vertical portions. It is quite evident that this constructive solution entails a considerable waste of time and high labor costs in addition to limited productivity. All the above described steps are in fact performed manually by assigned personnel. A considerable execution time is required particularly both by the step for placing the stirrups and the longitudinal rods of the frame, and by the step for fixing said rods to the stirrups. Another method in use entails the formation of panels made of electrically welded net. The longitudinal rods are normally added to the structure thus formed and fixed in the above described manner. Use of electrically welded net reduces the use of labor for tying, but has the considerable limitation that it is only suitable for frames having simple shapes and requires cutting the net panels to size, with a considerable waste of material and time. Devices are disclosed for the fabrication of reinforcing cages, either by tying or by welding structural rods to stirrups, in the documents WO-A-8705544 and WO-A-8505053. The aim of the present invention is to solve the above described problems by providing a method that allows to form metal frames for reinforced concrete in a simple and rapid manner. Within the scope of this aim, an object of the present invention is to provide a device that allows to automate the production of metal frames for reinforced concrete, with a structure that is simple in concept, safely reliable in operation and versatile in use. With this aim and this object in view, there is provided according to the present invention, a method for forming metal frames for reinforced concrete with the steps set forth in claim 1. The frame and lattice obtained with the method according to the invention have the features set forth in claims 4 and 8. Further details of the device according to the present invention will become apparent from the following detailed description of a preferred embodiment thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a partially cutout and partially sectional side view of the device for forming metal frames for reinforced concrete; figure 2 is a matching plan view thereof; figure 3 is a transverse sectional view thereof; figure 4 is a perspective view of a portion of a metal frame formed by means of the device according to the invention; figure 5 is a front view of a particular embodiment of said lattice, used to form the metal frame; figure 6 is a perspective view of a further embodiment of said lattice. With particular reference to the above figures, the reference numeral 1 generally designates the fixed framework of the device for forming metal frames for reinforced concrete, according to the present invention. The fixed framework 1 forms a longitudinal guide 2 on which a movable superstructure 3 is slideably mounted; the longitudinal guide 2 extends over a considerable length and is therefore only partially shown in the drawing. The movable superstructure 3 has a slider 4 which is mounted so that it can slide on a rail 5, formed by the longitudinal guide 2, under the actuation of appropriately motorized chain-drive means 6. The slider 4 supports freely rotating pairs of wheels 7 and 8 that respectively have vertical and horizontal axes, and engages the rail 5 by means of said wheels. The fixed framework 1 has, in a region for entering the longitudinal guide 2, a sort of portal which is formed by two lateral posts 9 mutually connected, at the base and at the top, by a pair of cross-members 10 and 11. The posts 9 and the cross-members 10 and 11 are similarly formed by metal profiled elements. Two shafts 12 and 13 are horizontally supported between the posts 9 and are respectively adjacent to the cross-members 10 and 11; two uprights 15, in turn formed by metal profiled elements, are slideably supported on the shafts 12 and 13 by means of associated bushes 14. The uprights 15 can slide along the horizontal shafts 12 and 13 independently of one another, are guided at the top by profiled members 16 surrounding the upper cross-member 11, and are guided at the bottom by plates 17 engaging the lower cross-member 10 on opposite sides; the uprights 15 can be locked in the desired working position by means of respective manual locking elements 18 and 19 that act at the guiding elements 16 and 17. The uprights 15 have, at their top, respective gearmotors 20 which rotate related shafts 21 which are threaded so as to form a worm and are mounted on said uprights 15 so that they can rotate vertically. Respective female-thread elements 22 are coupled to the worm shafts 21 and rigidly coupled to sliding blocks 23 which are guided so that they can slide vertically along the uprights 15. The rotation of the worm shafts 21, driven by the gearmotors 20, obviously produces the vertical movement of the sliding blocks 23. The sliding blocks 23 have a roller 24 which actuates related upper and lower limit switches, respectively 25 and 26, which are mounted at appropriate levels on the uprights 15. Respective bodies 27 are rigidly coupled to the sliding blocks 23 and extend horizontally forward toward the longitudinal guide 2 of the fixed framework 1, said bodies supporting respective lateral welding elements 28 which act along a horizontal axis lying transversely to said guide 2. The welding elements 28 are suitable to weld respective thin longitudinal auxiliary rods 29 on the outside of a series of stirrups 30 so as to form a lattice which is described more clearly hereinafter. Additional welding elements 31 are arranged in a downward region, in practice at the median longitudinal plane of the device, and are supported by a related body 32 fixed to the lower cross-member 10 of the framework 1. The lower welding elements 31, which act along a vertical axis, are suitable to weld a related auxiliary rod 29 to said stirrups 30. The lateral welding elements 28 respectively include a fixed welder 33 which is supported by an arm 34 rigidly coupled to the body 27 and a movable welder 35 that can be actuated axially by means of an actuator 36 mounted on said body 27. The lower welding elements 31 in turn have a fixed welder 37 supported by an arm 38 that is rigidly coupled to the body 32 and a movable welder 39 that can be actuated axially by means of an actuator 40 mounted on said body 32. It should be noted that the fixed welders 33 and 37 act as abutments for the action of the movable welders 35 and 39 on the inner side of the stirrups 30. However, it is possible to arrange the fixed welders on the outside of the stirrups 30 and vice versa make the movable welders act from the inside of said stirrups. For this purpose, the movable welders are conveniently supported by rotating arms so that they are rotated into a position for disengagement from the welding region for the insertion of the stirrups in said welding region. The stirrups 30 to be welded to the auxiliary rods 29 are placed manually on a welding table arranged transversely to the direction along which said auxiliary rods 29 are fed, so as to rest on a flat surface 41 and abut against respective lateral and lower locators 42 and 43. The locators 42 and 43 are rigidly coupled respectively to the arms 34 and 38 that support the fixed welders 33 and 37. However, it is possible to provide for the automatic feeding of the stirrups 30 to said welding table, particularly by means of elements for vertically transferring said stirrups onto said welding table. For this purpose it is necessary to provide, as mentioned earlier, welding elements that can rotate so as to clear the welding table when the stirrups are fed. The flat surface 41 for supporting the stirrups 30 is formed at the beginning of the longitudinal guide 2 and extends, longitudinally to said guide, with a rail 44 along which said stirrups slide during the formation of said lattice. It should be noted that inside the rail 44 there is an opening 45 in which the lower auxiliary rod of said lattice is arranged; the opening 45 furthermore affects the flat surface 41. The auxiliary rods 29 are unwound for example from appropriate reels or are supplied already cut to size; the rods 29 are fed in the welding region to the stirrups 30 after passing through related lateral and lower straightening elements provided with rollers, respectively 46 and 47. The lateral straightening rollers 46 are rotatably supported by a plate 48 which is rigidly coupled respectively to the sliding block 23 supporting the welding elements 28; the lower straightening rollers 47 are also rotatably supported by a plate 49 which is rigidly coupled to a profiled element 50 engaging the shaft 12. The auxiliary rods 29 are actuated at one end by related lateral and lower collet-like grip means, respectively 51 and 52, supported by the movable superstructure 3. Said grip means 51 and 52 substantially include a pin 52 that locks, upon actuation of a related locking lever 53, the end of the auxiliary rod 29 that is inserted in a bush 54 engaged by said pin 52. The lateral collets 51 are supported by a related annular slider 55; the sliders 55 are slideably mounted along a pair of vertical posts 56 of the movable superstructure 3 and can be locked in an adjustable position by means of respective manual locking elements 57. The posts 56 are in turn slideably supported by two horizontal shafts 58 and 59 which are rigidly coupled to the movable superstructure 3; the posts 56 can be locked in an adjustable position by means of associated manual locking elements 60. The lower collet 52 is instead rigidly coupled in fixed position to the movable superstructure 3. Optionally, the collets 51 and 52 can be supported so that they protrude from the movable superstructure 3, longitudinally with respect to the guide 2, and are close, during the initial step, to the region where the welding elements 28 and 31 act. The method for forming metal frames for reinforced concrete by means of the described device first of all entails the formation of a lattice comprising a series of stirrups 30 arranged on appropriately spaced parallel planes and mutually connected by at least two longitudinal auxiliary rods 29 which are welded externally to said stirrups 30. In figure 4 the stirrups 30 form a substantially square profile and are mutually connected by means of three auxiliary rods 29 which are arranged respectively on the sides and on the lower portion of the stirrups 30. This configuration matches the configuration of the device described above. In practice, the operator, after connecting the ends of the auxiliary rods 29 to the collets 51 and 52 of the movable superstructure 3, arranges in succession the stirrups 30 at the welding table formed by the flat supporting surface 41 and by the locators 42 and 43. The welding elements 28 and 31 are then actuated to weld the auxiliary rods 29 on the outside of the stirrup 30 which is arranged at said table. The mutual distance between the stirrups 30 is not necessarily constant but can change along the longitudinal extension of the frame according to the different requirements. The stepwise advancement of the movable superstructure 3, which is appropriately modulated according to the distance to be provided between the stirrups 30, pulls the auxiliary rods 29 and causes the matching advancement of the stirrup 30 that is welded thereto; the welded stirrup 30 advances while resting on the longitudinal guide 2 of the fixed framework 1. In this manner the welding region is cleared so as to allow the operator to insert the next stirrup to be welded. It should be noted that since said auxiliary rods 29 have a low thickness with respect to the stirrups 30, said stirrups are not affected by the welding step, which instead produces the local melting only of the auxiliary rods 29. Furthermore, the low thickness of the auxiliary rods 29 is such that it does not affect the intended embedding of the stirrups 30 in the concrete when the metal frame is installed. Generally speaking, auxiliary rods that have a diameter of 4 to 10 mm, preferably 5-6 mm, are used for stirrups having a diameter of 6 to 10 mm. Of course, the auxiliary rods 29 may have a flat shape or other similar shapes instead of a circular one. The lattice thus obtained is used to form the metal frame, inserting the conventional longitudinal rods or bars 61 inside the stirrups 30 and rigidly coupling said rods to at least some of them, for example at the inner corners of said stirrups 30. The rods or bars 61 are rigidly coupled to said stirrups 30 by means of conventional bindings 62. Naturally, the possibility of fixing the longitudinal rods or bars 61 to just some of the stirrups 30 allows a significant time saving in forming the frame, because, while in the conventional system it is necessary to fix all the stirrups to the longitudinal rods in order to keep said stirrups at the required distance, according to the present invention the stirrups are instead already fixed and spaced by virtue of their welding to the auxiliary rods 29, and therefore the bindings are required only to keep the longitudinal rods or bars 61 in position. For example, it is possible to reduce the bindings to be provided to approximately one sixth with respect to the conventional art, with a matching time saving. Furthermore, the stirrups can also be mounted in inverted position, i.e. so that the superimposed ends are directed on opposite sides, naturally preserving longitudinal symmetry. The fact should be noted that the auxiliary rods 29 are preferably arranged at the lateral portions of the stirrups 30 and at the lower portion thereof, i.e. on the opposite side with respect to the side for the insertion of the stirrups between said auxiliary rods 29, at said welding region, along a vertical feed direction. This allows, in particular, to automate said stirrup feed step, as mentioned. The same arrangement of the auxiliary rods 29 is provided for example in forming the lattice shown in figure 5, which has in particular five auxiliary rods 29. Said lattice is formed by means of stirrups 30a that form a double rectangle having a constant height and an appropriately differentiated width. In this case, too, the metal frame is naturally subsequently completed by inserting and tying the appropriate longitudinal rods inside the stirrups 30a, for example at the inner corners. In figure 6 the metal frame to be formed requires stirrups 30b that have a more complicated shape and form two rectangles elongated in perpendicular directions. The formation of the lattice, as shown, again entails the welding of an adequate number of auxiliary rods 29 on the outside of said stirrups. The fact should be stressed that use of the described device naturally entails greater benefits as the complexity of the stirrups to be joined to form the metal frame increases. The method and the device according to the invention ultimately allow to easily and rapidly form metal frames for reinforced concrete of any shape. In particular, the time saving that is achieved relates, as explained, both to the frame preparation step, avoiding the manual marking of the position of the stirrups and their placement, and the step for binding the longitudinal rods, by virtue of the reduced number of bindings required. In the practical execution of the invention, the materials employed, as well as the shapes and dimensions, may be any according to the requirements. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Method for forming metal frames for reinforced concrete, comprising the steps of: (a). arranging stirrups (30) that have a closed or open profile on appropriately spaced parallel planes; (b). inserting inside said stirrups (30) a series of longitudinal bars (61); and (c). rigidly coupling said bars (61) to said stirrups for obtaining the metal frame; characterized in that it further comprises, the additional step consisting in: (a1). positioning, at step (a) at least two longitudinal auxiliary rods (29) so as to be arranged at outside regions of said stirrups (30); and before the step (b), the intermediary step consisting in: (a2). fixing by welding on the outside of said stirrups (30) said least two longitudinal auxiliary rods (29) for the relative spacing and fixing of the stirrups at required distances so as to form a lattice; the final step (c) for the formation of the metal frame being carried out by tying the bars (61) to at least some of said stirrups (30) that formed with said auxiliary rods (29) said lattice. The method of claim 1, characterized in that the step (c), comprises rigidly coupling said bars (61) to only some of the stirrups (30) of said lattice in any known manner, as by tying or welding. The method of claims 1 or 2, characterized in that it further comprises: feeding in succession said stirrups (30) to a welding region where said auxiliary rods (29) are arranged; welding in said step (a2) said auxiliary rods (29) on the outside of said stirrup (30) inserted in said welding region; and actuating the stepwise advancement of said auxiliary rods (29) along a direction that is transverse to the plane of said stirrup (30), so as to prepare for the welding of a subsequent stirrup (30). Metal frame for reinforced concrete, comprising stirrups (30) with a closed or open profile, that are arranged on appropriately spaced parallel planes and a series of longitudinal bars (61) that are inserted inside said stirrups (30) and coupled thereto by tying, characterized in that is constituted by a lattice structure formed by said stirrups (30) with a closed or open profile, that are mutually connected by at least two longitudinal auxiliary rods (29) welded on the outside of said stirrups (30), said series of longitudinal bars (61) being coupled to said lattice by tying to at least some of said stirrups (30). Metal frame according to claim 4, characterized in that said auxiliary rods (29) are arranged at the lateral portions of said stirrups (30) and at a portion that is transverse to said lateral portions and is located on the opposite side with respect to the one where said stirrups (30) are inserted between said auxiliary rods (29), along an insertion direction lying on the same plane as said stirrups (30). Metal frame according to any of the claims 4 or 5, characterized in that said auxiliary rods (29) have a thickness selected in the range of 4-10 mm, preferably in the range of 5-6 mm, which is generally lower than that of the stirrups (30) having a preferred thickness range of 6-10 mm. The metal frame of claims 4 or 5, wherein the auxiliary rods (29) have a flat or other suitable shape. A lattice structure for inclusion in the metal frame for reinforced concrete of claim 4, comprising stirrups (30), with a closed or open profile, that are arranged on appropriately spaced parallel planes, characterized in that it further comprises at least two longitudinal auxiliary rods (29) welded on the outside of said stirrups (30) for the relative spacing and fixing of the stirrups at required distances. Device for forming the lattice structure of claim 8 for inclusion in the metal frame for reinforced concrete of claim 4, comprising a fixed framework (1) having a welding table (41, 42, 43) and welding means (28, 31) for welding longitudinal auxiliary rods (29) on the outside of stirrups (30) that have a closed or open profile and are arranged on said welding table (41,42,43) that lies transversely to the feeding direction of said auxiliary rods (29), and a movable superstructure (3) which is slideably mounted on a longitudinal guide (2) formed by said framework (1) and has means for gripping (51,52) said longitudinal auxiliary rods (29), said movable superstructure (3) being actuatable in modulated steps to form the lattice structure in which the stirrups (30) are arranged on appropriately spaced parallel planes and are connected by said longitudinal auxiliary rods (29), characterized in that said welding table comprises adjustably movable locator means (42, 43) cooperating with the rod gripping means (51, 52), for adjustably positioning the longitudinal rods (29) at said welding table (41, 42, 43) so as to be arrangeable as auxiliary rods (29) externally to, and on adjacent sides of said stirrups (30) whereby allowing insertion of said stirrups (30) between said auxiliary rods (29), means (15, 23, 34) for positioning said locator means (42, 43) and said welding means (28) in accordance with the stirrup profile to be welded at said welding table being further provided, said positioning means (15, 23, 34) being actuatable for adjustably moving both horizontally and vertically said welding means and said locator means (42, 43) for forming lattices with stirrups of any degree of complexity and various, either constant or differentiated, heights and widths. Device according to claim 9, characterized in that said positioning means comprise one or more pairs of vertical uprights (15) the position of which can be mutually independently adjusted on a plane transverse to said feeding direction of said auxiliary rods (29), said uprights (15) supporting, so that they can slide vertically, related sliding blocks (23) lockable in an adjustable position and respectively supporting said welding means (28), which are adapted to weld at least two longitudinal auxiliary rods (29) on corresponding lateral portions of said lattice, and said locator means (42, 43). Device according to claim 10, characterized in that said sliding blocks (23) support, upstream of said welding means (28), respective straightening elements with rollers (46,47) which are engaged by said auxiliary rods (29) to be welded on the outside of said stirrups (30). Device according to claims 10 or 11, characterized in that said uprights (15) have respective gearmotors (20) which rotate respective shafts (21) which are threaded so as to form a worm, said shafts (21) being rotatably mounted vertically on said uprights (15), and being coupled to respective female-thread elements (22) that are rigidly coupled to said sliding blocks (23) in order to adjust the vertical position of said welding means (28). Device according to one or more of the claims 10-12, characterized in that said locator means (42,43) are rigidly coupled to said sliding blocks (23). Device according to claim 9, characterized in that said welding means comprise lower welding means (31) arranged at the median longitudinal plane of the device and acting along a vertical axis to weld a related auxiliary rod (29) to a lower portion of said stirrups (30). Device according to claim 9, characterized in that said movable superstructure (3) has one or more pairs of vertical posts (56) the position of which can be adjusted mutually independently on a plane that lies transversely to said feeding direction of said auxiliary rods (29), said posts (56) supporting, so that they can slide vertically, respective sliders (55) lockable in an adjustable position and respectively supporting said rod gripping means (51, 52).

Inventors: MIGLIORANZA ARONNE, MIGLIORANZA, ARONNE
Applicants: SCHNELL SPA, SCHNELL S.P.A.
Application year: 1994
Main classification: B21F27
IPC codes: E04G21, E04C3, E04C5, B22D18, B21F27